Clinical Dermatology Terms


Acne is an inflammatory skin condition affecting the pilosebaceous units or “pores”. It will appear as pimples, blemishes, whiteheads, blackheads and in severe cases, deep, painful nodules and cysts. While teenagers are prone to this skin condition, it may affect people well into their 50’s especially if there are hormonal problems or stress. There may be several instigating factors to acne breakouts though today most cases of acne can be resolved. It is important never to pick or squeeze your blemishes as this can increase discoloration and scarring.

Actinic Keratosis

An actinic keratosis, also called AK, is a common precancerous skin growth. AK lesions are typically less than 1cm, and can be found on sun-exposed areas of the body. Most often, these lesions will feel scaly, like sandpaper. They may be red, pink or flesh-colored. While this type of lesion grows slowly, it is important to have actinic keratosis checked by your dermatologist. Left untreated, it may turn into a squamous cell carcinoma. These can be treated with ‘freezing’, a topical cream, or a special light.


Alopecia is the medical term for baldness. There are several different types of alopecia, with male pattern baldness being the most well known. Alopecia, however, may be present in locations other than the head. Depending on the type of alopecia, an individual may lose patches of hair or may lose all the hair on their body. Women may be just as susceptible as men to this condition, and the causes may be varied – from undernourishment to autoimmune disorders. A dermatologist can diagnose alopecia on sight and can determine the best form of treatment. Blood work and a complete medical history are important to identify the cause.

Alopecia Areata

Alopecia Areata is one form of baldness that may affect men or women of various ages. This type of alopecia may cause a person to lose patches of hair on their head, with one side of the head typically more affected than the other. Alopecia areata is thought to be caused by an abnormality in the immune system in which the body attacks certain hair follicles. Being an immune disorder, alopecia areata is genetic and hereditary, which means more than one person in a family may experience it. It may be seen in families with diabetes and thyroid disease. It can often be triggered by stress. Intralesional injections are often highly successful in restoring the hair.

Androgenetic Alopecia

Androgenetic alopecia is the most common form of pattern baldness known. This type of alopecia is not limited to male pattern baldness, however. Women may also experience pattern baldness, which is slightly different in that the hair at the crown of the head thins but the hairline does not recede. Androgenetic alopecia may be brought on by hormonal changes, aging and predisposition.

Acanthosis Nigricans

Acanthosis Nigricans is a skin condition that exhibits hyper-pigmentation of the skin. This hyper-pigmentation looks like darkened, velvety skin and is usually located in body folds. Acanthosis Nigricans will typically be found in the folds of the necks and groin, the axilla, forehead and around the belly button. This condition is normally seen in individuals over the age of forty, and may occur for several reasons. The most common causes of acanthosis nigricans may be obesity and endocrinopaties such as Cushing’s disease, hypo- or hyperthyroidism, and insulin-resistant diabetes.

Basal Cell Carcinoma

Basal cell carcinoma is a form of skin cancer that is slow-growing. It is the most common type of skin cancer in the United States today. Most instances of basal cell carcinoma occur on areas of skin regularly exposed to sunlight or other ultraviolet radiation. In the past, this type of skin cancer was seen mostly in adults over the age of forty. Today, these lesions are regularly seen on younger people. Those who may be more susceptible to basal cell carcinoma are people who are overexposed to the sun, have blue or green eyes, blond or red hair, or light-colored skin. While not usually dangerous, they can cause significant scarring and disfigurement if neglected.

Contact Dermatitis

Contact dermatitis occurs when the skin has come into direct contact with an irritating substance. The causes of contact dermatitis are varied. One may experience inflammation from substances such as solvents or adhesives, makeup or medications, detergents, nickel or other metals, or plants such as poison ivy or poison oak. Inflammation from contact dermatitis is not serious, but should be kept clean. This irritation may present as redness and swelling, a rash, or even lesions with oozing. Contact dermatitis itches, but if scratched, it is common to get a secondary infection, with is more serious.


Cysts are a very common ailment. They are often called ‘sebaceous cysts’. They arise most commonly on the backs of men but can affect woman also. The cyst will often discharge an odiferous, cheesy material. Treatment includes complete removal of the cyst so that it does not recur.


Dermatitis is an irritation to the skin. There are many various forms of dermatitis, and several causes that may bring about skin irritation and inflammation. Allergies to substances may be one cause, while dermatitis could also be brought on by eczema. Often, dermatitis will present as dry skin that is red and itchy. Occasionally this condition may cause swelling of the area where the irritation is present. Treatment varies based on the cause.

Dysplastic Nevus

A dysplastic nevus is simply an atypical mole. This type of mole may be larger than the norm, and typically has irregular borders. Dysplastic nevus may range from pink to dark brown in color. They are normally flat, but may also rise above the surface of the skin in some people. While dysplastic nevus should be checked by a dermatologist regularly, there is no proof that this type of mole is more prone to develop melanoma. They may, however, indicate an increased risk of melanoma, so regular body checks should be performed for early detection.


Eczema is a form of skin irritation that presents as dry itchy rashes. Atopic eczema is the most common form of this skin disorder. It occurs in people of all ages, differing in location depending on the age of the patient. In children, blisters or rash may occur on the scalp, face, hands and feet. In older children and adults, eczema rashes tend to appear in the insides of elbows and knees, sometimes on the hands. Itching is almost always a part of eczema, which is a hereditary skin condition. Treatment is determined by a dermatologist based on the severity of the condition and the age of the patient. Secondary infection is often a complicating problem with all forms of eczema.


Folliculitis is the inflammation of one or more hair follicles, which may occur anywhere on the body. This irritation begins when hair follicles become damaged due to blockage of the follicle or friction from clothing or shaving. Most cases of folliculitis also include follicles that have become infected with staph bacteria (Staphylococcus). Itching and redness may occur near the inflamed follicle.

Fungal Infections

Athlete’s foot, yeast infections and Ringworm are all forms of fungal infections that irritate the skin. Fungal infections such as athlete’s foot may cause symptoms like peeling, cracking, and scaling of the affected area, redness, blisters, itching, burning, or a combination of multiple symptoms. Fungal infections are treated based on the type of fungus affecting the skin.


Hirsutism refers to excessive hair growth in women. The hair growth characteristic of hirsutism follows male pattern hair growth, such as hair on the face or chest. This is a condition, not a disease in and of itself. It is important to discover the cause of excessive hair growth rather than seek ways to remove unwanted hair. The most common cause is androgen excess from polycystic ovarian syndrome.


A keloid is a type of scar, formed by the overgrowth of granulation tissue – basically, collagen. Keloids may be firm, rubbery lesions; or they may be shiny, fibrous nodules. They vary in color from pink to flesh-toned, to red or even dark brown. These scars are benign and non-contagious, but may be associated with itching and some difficulty in moving the affected skin. Recurrence is very common. Certain ethnic groups are more at risk for keloids, but all ethnicities can be affected.

Malignant Melanoma

Malignant melanoma is a tumor of melanocytes, the cells that produce the dark pigment, melanin. Melanoma may occur on any part of the body that has melanocytes, including the skin, eye and bowel. Malignant melanoma is one of the least common forms of skin cancer, but it is the most deadly form; accounting for almost 50,000 deaths per year. It is important to protect skin from the affects of UV rays and to receive regular checkups from a dermatologist in order to catch any sign of malignant melanoma early.


Melasma is a dark skin discoloration that occurs on sun-exposed areas such as the face, hands and chest or neck. Neither serious nor contagious, melasma is a pure cosmetic concern. In addition to sun exposure, melasma may also be caused by the female hormones estrogen and progesterone. Women taking birth control or hormone replacement therapy may are at increased risk of developing these dark spots. There are several treatment options available for this skin condition, but the recurrence rate is very high. Vigilant sun avoidance is mandatory.

Molluscum Contagiosum

This is a common viral condition most commonly seen in children. Various treatment modalities include applying a chemical to the lesions (i.e. beetle juice), freezing the lesions, or burning the lesions. This is a benign condition that does not require treatment but parents often request it.


Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of staph bacteria that resists antibiotic treatment. Typically, staph bacteria are treatable with antibiotics such as penicillin, amoxicillin and other beta-lactams. MRSA occurs very rarely, when the strain of staph causing the infection does not respond to typical antibiotic treatment. This is a very serious infection that requires immediate medical attention.


Psoriasis is a non-contagious condition in which skin becomes inflamed and thickened. It is believed that psoriasis may be hereditary, and that it may be due to the body’s immune system mistaking new skin cells as dangerous. Normally, new skin cells develop and rise to the surface in about 4 weeks, but in people with psoriasis, this process takes only 2 weeks. The result is a build-up of skin cells on the surface, which then turn dry and scaly. Psoriasis may be treated with medication, according to the severity of the condition. Decreasing carbohydrates and alcohol intake, as well as smoking cessation may help psoriasis.

Post-inflammatory Hyperpigmentation

Post-inflammatory hyperpigmentation occurs when the skin has experienced inflammation due to a pimple, rash or other irritation. When an inflammation occurs, an excess amount of melanin may be produced. Melanin is what gives skin color and excess melanin in a localized area will result in darker pigmentation. Hyperpigmentation is not a true scar and will likely fade over time, even without treatment. Because lightening may take several years, there are treatments available to speed up the process.


Rosacea is an inflammatory skin condition that is easily mistaken for acne by the untrained eye. With this condition, skin on the cheeks, eyes, forehead and chin may become inflamed and red, often resulting in skin eruptions like those associated with acne. Rosacea is associated with swelling of the blood vessels under the surface of the skin. There is no known cause of the condition, which tends to affect women more often than men. Certain ethnic groups seem to be affected more often than others. Flushing can be a stubborn symptom of this condition, and many exacerbating triggers have been identified. Alcohol, sun, stress and hot foods are common offenders.

Seborrheic Keratosis

Seborrheic keratosis (aka age spots) are wart-like growths that occur on the surface of the skin. These noncancerous growths tend to appear on the back, neck, shoulders, chest and face but may also occur on other parts of the body. Growths may exhibit a rough surface, much like a wart. There is no known cause, and treatment is not necessary unless the growth becomes uncomfortable or unsightly. Freezing is the usual treatment, but most insurance companies do not cover this procedure.

Seborrheic Dermatitis

Seborrheic dermatitis is inflammation of the skin thought to be caused by an irritation from a yeast called malessizia, as well as an overproduction of oil. A common form of seborrheic dermatitis is cradle cap, where thick scales form on the head of an infant. With Seborrheic dermatitis, skin builds up in certain oily areas of the body, such as the scalp, ears or eyebrows. Redness may occur; and affected skin may become itchy. Seborrheic dermatitis may have times of inactivity, followed by a flare up, which may be treated with medicated shampoo or lotion. Infants with cradle cap should be seen by their pediatrician.

Squamous Cell Carcinoma

Squamous cell carcinoma is one of the most common cancers in humans. Mostly known as a type of skin cancer, this carcinoma can actually also affect other large organs of the body and should be treated as early as possible. On the skin, they can be red, scaling and wart-like. They arise from untreated actinic keratosis. When treated early, squamous cell carcinoma typically poses no further problems. The main cause of this type of cancer is thought to be exposure to harmful UV rays. Treatment of squamous cell carcinoma is dependent upon the size, location and aggressiveness of the tumor. In rare cases SCC can cause death from metastasis to lymph nodes and lung.


Telangiectasias are small, dilated blood vessels that are easily seen on skin or mucous membranes. They may also be called spider veins. These spots may occur near the nose, chin, or in the eye. They may also occur on the legs, around ankles or below the knee. Causes may be congenital or acquired. Telangiectasias may be present in a person with rosacea, or may occur from pregnancy or a sedentary lifestyle. Treatment is available for telangiectasia and will be based on the location and severity of the condition.

Tinea Versicolor

Tinea versicolor is a common skin condition typically seen in young males and hot climates. The infection is caused by Pityrosporum ovale, a type of yeast that is normally found on human skin and in the scalp. While this yeast is present on most people, problems occur only in certain circumstances. With tinea versicolor, the skin develops patches of discoloration that may also feel scaly. Patches may be red-brown or white appearing on the back, chest, underarms and upper arms. Discoloration does not darken with sun exposure and sun actually makes it more noticeable. Antifungal creams may be used to treat tinea versicolor after diagnosis has been confirmed.

Viral Warts

Viral warts are soft, fleshy tumors caused by the human papiloma virus (HPV). There are several types of viral warts. Common warts typically occur on hands and feet, featuring elevated tissue. Plantar warts appear on the sole of the foot and are flat, growing down deeply into the skin. These can be quite painful. Flat warts can appear on the face and legs, posing cosmetic concerns. These flat warts are spread by shaving. Flat warts differ in color from the surrounding skin. Treatment for viral warts is dependent on type and severity, but cryotherapy (freezing) and desiccation (burning) are the most common methods. Warts are contagious.